Radio frequency identification architecture

• US 20020167405A1
• Filed: 02/12/2002
• Published: 11/14/2002
• Est. Priority Date: 02/12/2001
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Matrics Incorporated (Zebra Technologies Corporation)
• Inventors: Bandy, William R., Powell, Kevin J., Shanks, Wayne E., Arneson, Michael R.
• Granted Patent: US 6,989,750 B2
• Time in Patent Office: Days
• US Class Current: 340/572.1
• CPC Class Codes: G06K 17/00 Methods or arrangements for effecting co-operative working between equipments covered by two or more of main groups G06K1/00 - G06K15/00, e.g. automatic card files incorporating conveying and reading operations
• CPC Class Codes: G06K 19/0713 the arrangement including a power charge pump
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: G06K 19/07767 the first and second communication means being two different antennas types, e.g. dipole and coil type, or two antennas of the same kind but operating at different frequencies
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10039 interrogator driven, i.e. synchronous
• CPC Class Codes: G06K 7/10069 the collision being resolved in the frequency domain, e.g. by hopping from one frequency to the other frequency hopping or spread spectrum techniques H04B7/00
• CPC Class Codes: G06K 7/10108 interrogating only those RFIDs that fulfill a predetermined requirement, e.g. selecting all RFIDs having the same speed and moving in a cloud like fashion, e.g. on the same train; interrogating only RFIDs having a certain predetermined temperature, e.g. in the same fridge, another possibility being the active ignoring of a group of tags that fulfill a predetermined requirement, equivalent to the Boolean NOT operation
• CPC Class Codes: G06K 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas
• CPC Class Codes: G08B 13/2485 Simultaneous detection of multiple EAS tags
• CPC Class Codes: G11C 5/142 Contactless power supplies, e.g. RF, induction, or IR
• CPC Class Codes: H04L 7/0331 with a digital phase-locked loop [PLL] processing binary samples, e.g. add/subtract logic for correction of receiver clock H04L7/0337 takes precedence

Abstract

A radio frequency identification (RFID) architecture is described. RFID tags are interrogated by a reader, which may be located in a network of readers. The reader transmits symbols to the tags. Tags respond to the interrogations with symbols that each represent one or more bits of data. An RFID tag includes an antenna pad, a receiver, a state machine, and a modulator. The receiver is coupled to the antenna pad. The receiver receives a symbol from the antenna pad and outputs a received signal. The state machine is configured to determine a response symbol from the received signal and an operating state of the tag. The modulator is coupled to the antenna pad. The modulator is configured to backscatter modulate the received symbol with the response symbol. The modulator is configured to output the backscatter modulated symbol to the antenna pad.

Claims

1. A radio frequency identification (RFID) integrated circuit (IC), comprising:

a first antenna pad;

a second antenna pad;

a first modulator coupled to said first antenna pad, wherein said first modulator is configured to backscatter modulate a first symbol received from said first antenna pad with a response symbol, wherein said first modulator is configured to output said backscatter modulated first symbol to said first antenna pad; and

a second modulator coupled to said second antenna pad, wherein said second modulator is configured to backscatter modulate a second symbol received from said second antenna pad with the response symbol, wherein said second modulator is configured to output said backscatter modulated second symbol to said second antenna pad.

2. The RFID IC of claim 1, further comprising:

a first receiver coupled to said first antenna pad, wherein said first receiver receives said first symbol from said first antenna pad and outputs a first received signal; and

a second receiver coupled to said second antenna pad, wherein said second receiver receives said second symbol from said second antenna pad and outputs a second received signal.

3. The RFID IC of claim 2, further comprising:

a state machine configured to receive said first received signal and said second received signal and generate said response symbol.

4. The RFID IC of claim 3, further comprising:

a data programming unit that stores a tag identification number.

5. The RFID IC of claim 4, wherein said state machine is configured to read said stored tag identification number, wherein said state machine is configured to generate said response symbol using said first received signal, said second received signal, and a bit of said read tag identification number.

6. A radio frequency identification (RFID) integrated circuit (IC), comprising:

an antenna pad; and

a modulator coupled to said antenna pad, wherein said modulator is configured to backscatter modulate a symbol received from said antenna pad with a response symbol, wherein said modulator is configured to output said backscatter modulated symbol to said antenna pad.

7. The RFID IC of claim 6, further comprising:

a receiver coupled to said antenna pad, wherein said receiver receives said symbol from said antenna pad and outputs a received signal.

8. The RFID IC of claim 7, further comprising:

a state machine configured to receive said received signal and generate said response symbol.

9. The RFID IC of claim 8, further comprising:

a data programming unit that stores a tag identification number.

10. The RFID IC of claim 9, wherein said state machine is configured to read said stored tag identification number, wherein said state machine is configured to generate said response symbol using said received signal and a bit of said read tag identification number.

11. A radio frequency identification (RFID) tag device, comprising:

a first antenna;

a second antenna;

a first receiver coupled to said first antenna, wherein said first receiver is configured to receive a first symbol from said first antenna, and wherein said first receiver is configured to generate a first received signal;

a first modulator coupled to said first antenna, wherein said first modulator is configured to backscatter modulate the received first symbol with a response symbol, wherein said backscatter modulated first symbol is output to said first antenna;

a second receiver coupled to said second antenna, wherein said second receiver is configured to receive a second symbol from said second antenna, and wherein said second receiver is configured to generate a second received signal;

a second modulator coupled to said second antenna, wherein said second modulator is configured to backscatter modulate the received second symbol with the response symbol, wherein said backscatter modulated second symbol is output to said second antenna; and

a state machine coupled to said data programming unit and said first and said second receivers.

12. The RFID tag device of claim 11, wherein said state machine is configured to receive said first received signal from said first receiver and to receive said second received signal from said second receiver, wherein said state machine generates said response symbol.

13. The RFID tag device of claim 12, further comprising:

a data programming unit that stores a tag identification number.

14. The RFID tag device of claim 13, wherein said state machine is configured to read said stored tag identification number, wherein said state machine is configured to generate said response symbol using said received signal and a bit of said read tag identification number.

16. The RFID tag device of claim 15, wherein said state machine is configured to receive said received signal from said receiver, wherein said state machine generates said response symbol.

17. The RFID tag device of claim 16, further comprising:

a data programming unit that stores a tag identification number.

18. The RFID tag device of claim 17, wherein said state machine is configured to read said stored tag identification number, wherein said state machine is configured to generate said response symbol using said received signal and a bit of said read tag identification number.

20. The tag of claim 19, wherein said means for communicating includes means for concluding said binary traversal algorithm when a received symbol is a “

NULL”

symbol.

15. A radio frequency identification (RFID) tag device, comprising:

an antenna;

a receiver coupled to said antenna, wherein said receiver is configured to receive a symbol from said antenna, and wherein said receiver is configured to generate a received signal;

a modulator coupled to said antenna, wherein said modulator is configured to backscatter modulate the received symbol with a response symbol, wherein said backscatter modulated symbol is output to said antenna;

a state machine coupled to said data programming unit and said receiver.

19. An identification (ID) tag, comprising:

a substrate having an input capable of receiving a high frequency signal;

a first charge pump coupled to said input and disposed on said substrate, said first charge pump configured to convert said high frequency signal to a substantially direct current (DC) voltage;

means for storing a bit pattern;

a data recovery circuit coupled to said input and disposed on said substrate, said data recovery capable of recovering data from said high frequency signal;

a backscatter switch coupled to said input and disposed on said substrate, said back scatter switch capable of modifying an impedance of said input and responsive to a control signal;

a state machine disposed on said substrate and responsive to said data recovered by said data recovery circuit, said state machine generating said control signal for said backscatter switch in response to said data;

said DC voltage from said first charge pump capable for providing a voltage supply for at least one of said data recovery circuit, said backscatter switch, and said state machine; and

means for communicating with a reader using a binary traversal algorithm, said binary traversal algorithm comparing bits within the bit pattern to symbols received from said reader.